


A Study in Blue

by bumblebi221



Category: Supernatural
Genre: Alternate Universe - Detectives, Detective Castiel (Supernatural), M/M, Marine Corps Dean Winchester, Prompt Fill, Sherlock AU, Tumblr Prompt
Language: English
Status: Completed
Published: 2021-02-26
Updated: 2021-02-26
Packaged: 2021-03-17 17:22:05
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,076
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29720634
Author URL: https://archiveofourown.org/users/bumblebi221/pseuds/bumblebi221
Summary: Prompt for @imapala67-aka-baby on Tumblr: Can you write like a monster free AU where cas is a detective (like sherlock, new to emotions, takes things way too seriously, and lives alone because he's weird) and dean is like an ex-marine or something who comes to live with him… and they like go on a case where someone is killed. And Cas kind of doesn't understand the need of emotions to the victim's spouse and they both solve the case using their own weird ways which nobody else understands (Cas's observational skills and Dean's field skill)... At the end of the case they realize both of them like each other's weirdness but Cas asks Dean to leave because he doesn't get emotions also because he doesn't understand what's so special about dean and Dean says that he will teach cas about emotions and it ends with them both knowing that this is start of something new for both of them.
Relationships: Castiel/Dean Winchester
Comments: 1
Kudos: 11





	A Study in Blue

“Dean? Dean Winchester!” Dean, in the middle of a solitary walk in the park, turned around to see a short, red-haired woman running after him, waving. He knew this short, red-haired woman.

“Charlie!” he grinned. “Long time, no see!”

“Yeah, where’ve you been?”

“Overseas. Enlisted in the marines, but I got shot.” He gestured to his cane. “I hate this thing.”

“Oh man, that sucks. So now you’re back?” Dean nodded. “Have you found a place yet?”

“Not yet, Sammy offered to let me stay at his place but I want to try to get one on my own first.” Charlie’s face lit up.

“Oh! I know a guy you could stay with! He’s around your age, and he’s a good guy. He's a little weird, but he grows on you when you get to know him.”

“Thanks, Charlie. Do you know how I can contact him?”

“Actually, he’s probably hanging around the hospital if you want to meet him now. Unless you’re busy?” Dean chuckled.

“No, not busy at all. How did you meet him?”

“Friend of a friend,” she answered mysteriously, grinning. The two set off for the hospital, chatting about Charlie’s new girlfriend, current events, and other missed conversations. She refused to tell Dean anything more about his prospective roommate, and Dean was itching to learn more. Thankfully, he didn’t have to wait long, as they arrived and headed for the elevator. Charlie, much to Dean’s confusion, hit the button for the basement level. They stepped out and made their way down the hallway to a big cold room with two people in it. One was clearly a doctor, but the other - the one Charlie took him to meet, Dean was guessing - was wearing a beige trench coat and seemed to be experimenting on the corpse. They were in a morgue. They were in a morgue with a trench coat-wearing man who was currently pouring some fizzy substance into an open wound on a corpse. Great.

“Hey, Castiel!” Charlie waved as the trench coat man - Castiel, apparently - turned around, seemingly confused and possibly a tad annoyed as to why he was being interrupted.

“Charlie,” he greeted. His voice was gruff and deep, not what Dean had expected at all. “What are you doing here? No, wait. Let me guess.” He turned to Dean and looked him up and down, taking in the stranger. Dean tried not to squirm under the scrutiny. Castiel looked into his eyes for what felt like a long time before he finally spoke. “You’ve been in the Pacific.” Dean froze.

“Wh- how did you…?” he trailed off. He turned to Charlie for answers, but she only smiled mischievously. 

“I’ve found an apartment downtown that I think we can afford. I’ll meet you there tomorrow,” Castiel said. He turned to leave, having apparently forgotten about his experiment. He was nearly at the door when Dean finally got up the nerve to speak.

“No, hang on. I don’t know anything about you, except a name - Castiel, right? - and that you like to pour liquids into dead guys. Who are you? What do you do? How did you know we were here for that? And where are we meeting? You didn’t even give me an address for the apartment, man!”

“This morning I told Charlie that there wasn’t anyone in the world who would live with me. Now she’s here with someone I’ve never met, who she clearly hasn’t seen in a while. You’ve been abroad and need a place to stay. Simple. My name is Castiel Novak. The apartment is at 51 Meadow Street. I’ll see you there tomorrow. Bye, Charlie.” And with that, the enigma of a man left.

“My - my name is Dean,” he called after him, though he wasn’t sure if Castiel heard him or not.

“Like I said,” Charlie grinned. “He grows on you.” Dean nodded warily. This was sure to be interesting.

The next day, thanks to Charlie’s help, Dean arrived on time for his meeting with Castiel. Although he hadn’t been given an exact time, Charlie had texted Castiel and managed to get one. From the outside, the apartment looked nice enough, but Dean still didn’t know much about Castiel, so he was a little hesitant. Dean was wondering if he’d gotten the time wrong when an old Lincoln Continental pulled up and out stepped Cas. He seemed not to take any notice of Dean.

“Castiel?” Dean approached him, waving amicably. “It’s me. Dean. From yesterday.”

“Ah, yes. Hello, Dean.”

“This looks like a good place, how are we going to afford it? I haven’t found a job yet, so -”

“The landlord’s offered me a special deal. I was able to track down the villain who murdered his wife a while back.” Just then, the door opened to reveal an older-looking man with a beard and a trucker hat.

“Castiel,” he greeted warmly, pulling him into a hug. Castiel looked fairly awkward.

“Hello, Bobby,” he said, moving out of the hug. “I’m here about the apartment. I’m going to be renting it with this young man.” He gestured towards Dean.

“Dean,” he told the landlord, extending a hand. Bobby took it.

“Pleasure to meet you, Dean.” Bobby smiled. “Well, let’s not waste any more time out here yapping like a gaggle of old ladies. Come on in.” Dean and Castiel followed behind Bobby as he led them up the stairs and down the hall towards 2C. The apartment was nice. It had two bedrooms and a bathroom, and the kitchen was awesome - Dean enjoyed cooking before he’d been deployed, so he was happy he had a decent place to get back into practice.

“So, Cas, how about that murder uptown?” Bobby said. “I saw it in the paper. Looked like your kind of gig.”

“Yes, I expect a call from the police captain will be coming in shortly regarding that murder.”

“Police captain?” Dean asked, not sure he heard right. Sam was police captain.

“Yes, Captain Winchester. He’s not as clever as one would want from the police captain, but he’s the brightest in the precinct.” Castiel was staring out the window down to the street below.

“Captain Winchester’s my brother,” Dean said, not sure whether to take Cas’ words as an insult or a compliment. This caught Cas’ attention. He turned around to face Dean.

“You’re Dean Winchester?” Dean nodded. “Captain Winchester’s told me a lot about you. I feel so stupid for not figuring it out sooner.” Dean could see that Castiel indeed looked flustered and embarrassed.

“Don’t worry about it. You still seem real smart to me. How did you guess I was in the Pacific, anyhow?”

“It was simple. Your haircut and posture give away the armed forces immediately. Your tan suggests somewhere sunny. You have a typical marine tattoo, the one with the bird, that I can just make out under your t-shirt. The rock on one of your necklaces is a volcanic rock, suggesting an island. Pacific.”

“Well, now that you explain it, it seems simple.” Castiel sighed and rolled his eyes. Dean realized that wasn’t the nicest thing to say. “Still. Don’t think many people could do that. Nice work.” Castiel gave a small smile.

Just then, the doorbell buzzed, and a few minutes later there was a knock at the door. Dean peered through the peephole to see Sam standing there, looking impatient and frustrated. He opened the door with a grin.

“Sammy!” he greeted, moving in for a hug. “Nice to see you!” Sam obliged the hug for a few seconds, but quickly squirmed away, approaching Cas.

“Cas? When did you move in with my brother?” Sam looked confused, but shook his head as if clearing his thoughts. “Whatever. I need your help.”

“The murder?”

“You read my mind.”

“People tend to think that,” Castiel said, though he didn’t seem to be bragging.

“So, you coming?”

“Give me a minute. I’ll meet you downstairs.”

“Got it. See you.” Sam turned to Dean. “And I’ll talk to you later.” He left, and Castiel waited for the footsteps to fade before turning to Dean.

“Isn’t this amazing? This week was threatening to be incredibly boring before your brother turned up.” Indeed, Castiel looked like it was his birthday or something. “Don’t bother waiting up, this could take a while. Feel free to move in and get comfortable. Goodbye.” Castiel was halfway out the door when he turned back.

“Unless…” Castiel trailed off, looking into the distance.

“Unless what?” Dean asked.

“You could come with me. It might be… useful. To have an ex-marine around.”

“What makes you say so?” Castiel didn’t seem to hear him, but continued rambling on.

“Although, you’ve probably seen too much violence.”

“Yeah, you could say that.”

“Still, it’d be nice to have you around.”

“I’ll consider it.”

“Really nice.” Castiel dragged out the really, still looking into the distance. Then, with a headshake, he returned to the present and quickly left the room. Dean sighed and followed him.

“Fine.”

It was late in the evening when Dean and Castiel returned to their new apartment. Dean was exhausted. He had spent all day tagging along with Castiel and Sam as they tried to find the murderer. Castiel had insulted the victim’s spouse twice and run off without warning twice, leaving him trying to catch up. But the worst part was when they’d found the murderer. Castiel and Sam had chased after him, but in their haste they’d gotten themselves surrounded - the murder, it had turned out, was a group thing. Castiel and Sam were surrounded by five angry men who weren’t about to listen to reason. He heard Sam yell for help, and then… he dropped his cane. And he ran. He didn’t think of how to unpack that; his only thoughts were on Castiel and Sam. He drew his gun and hit three over the head before the remaining two bad guys caught on, but by that point they were outnumbered. Dean held his gun to their original suspect’s head while Castiel pinned the other guy to the floor. Sam called for backup, and before long, Dean and Castiel were walking home in the dark and cold.

“That was brave, Dean,” said Castiel after several minutes of silence.

“It was nothing. Don’t worry about it.” Dean looked down at his shoes, but if he hadn’t, he would’ve seen Castiel look down, too.

“It wasn’t nothing,” he said quietly.

When they got back, Bobby scolded Castiel for being home so late, and gave Dean a look of “I can’t believe I’m going to have to keep an eye on you, too” before heading to bed. Dean and Castiel went up to their apartment. Castiel showed no signs of exhaustion, but he was remarkably quiet. Dean had spent all day listening to him ramble about the case, and he found quiet Castiel to be slightly concerning.

“Castiel, are you okay?” Castiel turned towards him. His eyes were vivid blue, and they were angry.

“You need to go,” he said, spitting the words like venom. Dean’s eyes widened in shock.

“Wh- why?” he sputtered.

“Because. I need to focus on my work. And, while you may have some uses, ultimately I must remain vigilant and alert to the task at hand.”

“Have some uses?” Dean said, voice rising both in pitch and volume despite his best efforts to keep it level. “People aren’t tools.”

“No. But they are a distraction.” Castiel walked over the window and looked down at the street below. His shoulders sank an almost imperceptible level, but Dean noticed, and realized the mood change. He came up behind him, and put a hand on the detective’s shoulder.

“Cas,” he said, and he realized he hadn’t called him that before. “Cas, are you sure that’s what this is about?” Cas didn’t answer.

“My whole life, I’ve tuned out people, I’ve had no trouble feeling nothing towards them - because emotions are a distraction, you know - but you show up in the morgue, and I…” he trailed off. “You’re different. And I don’t… I can’t figure out what that means.” He turned to look at Dean, and Dean could see Cas’ eyes were quivering and shiny.

“Hey,” Dean said, eyes softening. “I, uh… I felt something, too. And I’ve never felt that way before, either - well, about a man, anyway. Maybe we can figure this out together?” Cas gave a tentative smile.

“I’d like that, Dean.”


End file.
